North Carolina ? A farm in western North Carolina has been quarantined after a chemical blamed for more than a dozen pet deaths was found in its hogs, state officials said Wednesday. None of the hogs has entered the food supply.

The farm received a shipment of contaminated feed last week, said Mary Ann McBride, assistant state veterinarian for the North Carolina Department of Agriculture and Consumer Services in Raleigh. It was the only farm in the state that received the feed.

State officials took urine samples from 13 hogs, and all tested positive for melamine, a chemical used to make plastics and foam, McBride said. The farm, which wasn’t identified, has about 1,400 hogs, she said.

The U.S. Department of Agriculture’s Food Safety and Inspection Service has said fewer than 10 hog farms in six states received contaminated feed. The feed came from a Diamond Pet plant in Gaston, S.C.